Indium-Promoted ZnZrO<sub><i>x</i></sub> Solid Solution Catalyst for CO<sub>2</sub> Hydrogenation to Methanol
Zixuan Zhou, Zhangqian Wei, Jian Zhang, Haiyan Yang, Shenggang Li, Peng Gao
Abstract
Methanol synthesis is one of the most important and industrially viable approaches to carbon dioxide (CO 2 ) utilization. Both the ZnZrO x (ZZO) solid solution catalyst and the In 2 O 3 catalyst have garnered extensive attention for their high methanol selectivity and excellent resistance to sintering and sulfur in CO 2 hydrogenation. Herein, a ZZO solid solution with a large surface area is selected as the carrier, and the supported In 2 O 3 strongly interacts with the ZZO to boost the generation of more oxygen vacancies on the ZZO surface that catalyzes methanol production. On incorporating an appropriate amount of In 2 O 3 (In 2.5 wt %) onto the ZZO catalyst, In 2.5 /ZZO exhibits markedly enhanced methanol production with a CO 2 conversion rate of 13.5% and a methanol space-time yield of 0.749 g g cat –1 h –1 at 330 °C, 5 MPa, and 24,000 mL g cat –1 h –1 . In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveals that the incorporated indium species facilitate hydrogen activation to increase the availability of surface hydrogen. The surface hydrogen is transferred to the active sites due to hydrogen spillover, facilitating the formation of HCOO* intermediates and boosting the hydrogenation of CO 2 to methanol. Theoretical analysis allows the rationalization of the observed improvement in the catalytic performance of the In 2.5 /ZZO catalyst. In 2.5 /ZZO showed excellent stability for up to 200 h on stream, demonstrating its potential as a practical catalyst for the hydrogenation of CO 2 to methanol.